Etching machine



Sept. 25, 1951 w. GUENST ETCHING MACHINE Filed June 9, .1949

2 Sheets-Sheet 2 INVENTOR Patented Sept. 25, 1951 UNITED-STATES PATENT OFFICE 2,568,803 ETCHING MACHINE William Guenst, Wyncote, Pa. Application June 9, 1949, Serial No. 97,939

' Claims. (o1. 41-9) The present invention relates to an etching process and machine.

The purpose of the invention is to provide better control of the application of etchant during etching and particularly during re-etching, and

especially to permit instantaneous cut-off of Z etchant flow and secure rapid removal of all of application, preferably with finger tip control of theapplication of the etchant.

A further purpose is to provide both an etchant tip and a vacuum tip in an etching pen, and desirably to make the etchant tip of resilient tubing and use a bend in the rubber tubing exposed to the pressure of the finger as a valve.

A further purpose is to take the etchant out 3f the vacuum stream continuously by an etchant rap.

A further purpose is to provide a simple pump such as a syringe bulb to start flow from an etchant vessel to an etching pen.

j A further purpose is to provide return of etchant from the etchant trap to the'etchant vessel by suction.

.A further purpose is to adjust the size of the etching area by applying various sizes of tips in the vacuum tip, thus conveniently adjusting the effectiveness of the vacuum in withdrawing etchant from the etching area.

Further purposes appear in the specification and in the claims.

, In the drawings I have chosen to illustrate a few only of the numerous embodiments inwhich my invention may appear, selecting the forms shown from the standpoints of convenience in illustration, satisfactory operation and clear demonstration of the principles involved.

Figure 1 is a diagrammatic elevation of my improved etching machine.

Figure 2 is a diagrammatic side elevation showing the machine of Figure 1 mounted on a portable support.

Figure 3 is an enlarged central axial section of the etching pen.

Figure 4 is a fragmentary enlarged axial section of the pen showing a modification in the structure of Figure 3.

Figure 5 is a section of Figure 4 on the line 5-5.

Figures 6 and 7 are fragmentary axial sections corresponding to Figure 3, showing variations in the construction of the pen.

Describing in illustration but not in limitation and referring to the drawings.

In the prior art considerable difficulty has been encountered in obtaining adequate control of etching solutions, especially in etching printing plates and more particularly in re-etching the same.

In the graphic arts, extensive use is made of the principle of applying a resist to a printing plate and then etching the same, usually with an acid or acid salt. When reference is made herein to a printing plate, it will be understood, of course, that the plate need not necessarily be flat, but may and often will be a cylinder or segment of roll.

Special skill is required in the application of the etchant, especially when re-etching is being carried on for repair purposes or the like, and it is very desirable to permit the etcher to confine the area to be etched to an extremely limited area, and likewise to permit the etcher to out 01f instantly the flow of etchant, and immediately remove any excess, and then again reapply etchant to the same or a different area. The etchant which is widely used and may be considered typical for the purposes of the present invention is ferric chloride or ferric chloride made acid by hydrochloric acid, but it will be understood that any other suitable etchant may be employed. The metal etched may be any of the metals commonly employed in printing plates, such as copper, steel, stainless steel, Monel, brass, bronze or aluminum alloy.

By the present invention the etcher can turn on the acid stream instantaneously and turn it 01f without delay, and immediately remove excess etchant, and can confine the area being etched to a very small area as desired. At the same time the re-use of the etchant is facilitated without requiring direct handling of the corrosive liquid.

' The etchant 20, suitably ferric chloride solution, is contained in an etchant vessel 2 l suitably a glass bottle conveniently provided with a fourhole rubber stopper 22. From the bottom of the vessel extends an etchant discharge tube 23, which, after passing through the stopper, con- 'nects with an etchant tube 24, suitably of resilient material such as acid resisting rubber or resilient acid resisting plastic, which extends to the etchant tube 25, suitably also of resilient tubing like acid resisting rubber or-plastic, of a pen '26. The tube 25 terminates at the forward end of the pen at an etchant tip 21, which is suitably cut at an angle to the axis of the pen at about 30 to 60 degrees as shown. The pen includes a pen holder 28 having a longitudinal tubular passage 30 through which the etchant tube 25 passes. At an intermediate point, convenient to the finger tip of the user, side openings 3! from the passage 30 are provided along with a thickened cross rib 32 between the openings, and the tube 25 is bent outwardly in a loop through the openings 3| and over the rib 32 so that it is exposed on the outside as seen best in Figure 3. The user, by bringing pressure of the finger tip against the resilient tube, is able to flatten out the tube, so that the combination of the tube and the rib acts as a valve for the etchant.

Also passing throughthe stopper 22 of the etchant vessel is a tube 33 terminating near the top of the interior of the vessel and connecting as by a resilient tube 34 to a suitable pressure pump 35 for expelling the etchant.

The pump 35 may conveniently be an atomizer bulb provided with the usual check valve to admit air, which can exert a slight pressure on the interior of the etchant vessel to start siphoning of etchant into the pen (the pen being used at a position below the etchant vessel). be understood that any other suitable pump can be used.

A vacuum pump 36, driven by a motor 31, controlled by an electric foot switch 38, connects by It will tubing with a separator vessel 4| through which the tubing enters suitably near the top by means of one of the openings in a rubber stop per 42. From an intermediate portion of the separator vessel 4|, connection is made through the stopper 42 by tubing 43 and a normally open valve or cook 44 into the top of an etchant trap 45, suitably entering through one of the holes in a rubber stopper 4E. The tube 43 terminates near the top of the trap 45. From a suitable, preferably intermediate point in the trap 45 a tube 4! extends through the stopper and makes connection with a suitably resilient vacuum tube 48, which extends to the pen and there makes connection with a vacuum tube 50, which passes through a longitudinal passage 5| of the pen holder and terminates in a vacuum tip 52, preferably cut diagonally at an angle of between'30 and degrees to the axis of the pen holder. The angle of the etchant tip is preferably turned outwardly and opposite to the angle of the vacuum tip so that the tube tips tend to cause a slight divergence in the hydraulic flow at the tips.

In order to assist in the return of etchant, which is normally capable of re-use, to the etchant vessel, a tube 53 extends from the bottom of the etchant trap through the stopper 46 and, connected by intermediate tubing, through a normally closed valve or cook 54 and the stopper 22 to a suitable intermediate point in the height of the etchant vessel. Likewise through tubing 55 and a normally closed valve or cook 56 connection is made between the top of the etchant vessel and an intermediate point in the separator 4|.

In operation of the form of Figure 1, the user places the pen adjacent the work in a position below the bottom of the etchant vessel. He starts the vacuum pump by pressure on the foot switch 38 and applies slight positive pressure on the etchant in the etchant vessel by squeezing the atomizer bulb or pump. This starts siphoning of etchant to the etchant tip and suction removal of etchant by the vacuum through the vacuum tip and tubing into the trap 45, where recovered etchant collects. The strength of the vacuum is regulated so that it removes the etchant more slowly than the etchant tip applies it.

The user then applies the stream or spray of etchant to the work at the point desired, keeping a finger tip adjoining the valve loop of the etchant tube 25, and squeezing the etchant tube whenever it is desired to cut off the flow or retard the flow of etchant. When the etchant is cut ofi", the suction, which is applied at a point longitudinally beyond the etchant tip, will remove all excess etchant. The vacuum tip is thus always close to the work.

Figure 3 shows the application of the etching to a printing plate 51.

During the normal operation of the pen, recovered etchant collects in the bottom of the trap 45. The separator 4| provides protection to the vacuum pump by avoiding the danger of having etchant entrained in the air entering the vacuum pump. Normally the separator 4| re mains dry.

After extensive use of the pen, the level of etchant 20 in the vessel 2| will be lowered, While etchant will collect at 58 in the trap 45. To return the etchant 58 to the main body of etchant 20, the valve 44 is closed, while the valves 54 and 56 are opened. The valve 5!; permits suction to be applied to the interior of the etchant vessel 2| and the open valve 54' permits etchant 58 to be drawn into the main body of etchant 20. When the etchant has been properly returned to the main body, the valves 54 and 56 are again closed, and the valve 44 is opened, the device then being ready for further etching.

In the form of Figure 2 a base 6|], on which the various containers are shown supported in Figure l, is provided with a cage 6| to hold the vessels and mounted on an adjustable pedestal 62 from a portable truck 63 carrying the vacuum pump on a platform 64. Otherwise the mechanism is the same as that of Figure 1. The work in Figure 2 is a printing cylinder 51'.

In some cases it is desirable to reduce the vacuum effect. In this case a removable reducer tip 65 is shown inserted'in the normal vacuum tip 52 to localize the point of suction application. The tip 55 will be one of a. series of various sizes of tips having different tip diameters which can be substituted.

In some cases it may be desirable to substitute a different type of finger tip valve. In Figure 6 a valve 66 is shown acting to pinch the tube 25, urged toward closing by a spring 61 and opened by a stem 68 pivotally connected at 10 to a lever H on a fixed pivot 12. The finger engages the valve lever at 13.

In Figure '7 the valve 66, acting to pinch the tube 25, is urged toward opening by a spring 6'! and closed by a stem 58 supporting a. push button I4 contacted by the finger tip. It will be evident that other suitable valves may be employed as desired.

It will be evident that it is advantageous to extend the vacuum tip closer to the work than the etchant tip, so that the stream of etchant projected from behind the vacuum tip is taken away by the vacuum tip operating close to the surface of the printing plate.

In view of my invention and disclosure, variations and modifications to meet individual whim or particular need will doubtless become evident t0 ot e i d n the art, to obtain all or pa t of the benefits of my invention without copying the process and structure shown, and I, therefore, claim all such insofar as they fall within the reasonable spirit and scope of my claims.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. An etching pen comprising a tip for discharging etchant to the object to be etched, a

tip for applying vacuum adjacent the tip for applying etchant and a holder for both tips.

2. An etching pen comprising a tip for applying etchant to an object, a tip for applying vacuum to the object adjacent the tip for applying etchant, a holder for both tips and a valve under control of the finger-tip connected to the tip for applying etchant to cut off the flow of etchant under finger-tip control.

3. In an etching pen, a holder, and a resilient tube for etchant extending through the interior of the holder to a tip at the end of the holder, there being a loop in the tube exposed on the outside of the holder for contact with the finger of the user and a portion of the holder behind the loop to pinch the tube in order to act as a valve.

4. An etching pen comprising a holder, a resilient tube extending through the holder to a tip at the end of the holder and having a bend exposed at the outside of the holder for engagement by the finger-tip to pinch the tube and act as a valve, and a vacuum tube extending through the holder to a tip at the end of the holder adjoining the etchant tip.

5. An etching pen having a holder, an etchant tip in the holder, a valve for controlling the etchant tip, a vacuum tip in the holder adjacent the etchant tip and a reducing tip removably insertable in the vacuum tip.

6. In an etching pen, a pen holder, an etching tip in the end of the pen holder, having the tip diagonally ended and a vacuum tip in the end of the pen holder adjoining the etching tip having the vacuum tip diagonally ended oppositely from the etching tip.

7. In an etching pen, a pen holder, an etching tip in the end of the pen holder and a vacuum tip in the end of the pen holder extending forward beyond the etching tip.

8. In an etching machine, a vessel for etchant, an acid trap, a pump connected to the vessel for etchant, a vacuum pump connected to the etchant trap, an etching pen having an etchant tip, having a valve controlling fiow through the etching tip and having a vacuum tip, a connection from the bottom of the vessel for etchant to the etching tip through the valve and a connection from the etchant trap to the vacuum tip.

9. In an etching machine, a vessel for etchant, a pump connected to the vessel for etchant, an etchant trap, an etchant pen having an etchant tip, having a valve controlling flow of etchant through the etchant tip and having a vacuum tip, a vacuum pump connected to the acid trap, a connection from the bottom of the vessel for etchant to the etchant tip through the valve in the tip, a connection from the acid trap to the vacuum tip, an etchant return connection including a valve from the bottom of the acid trap to the vessel for etchant and a return vacuum connection including a valve from the vacuum pump to the upper portion of the vessel for etchant.

10. In an etching machine, a vessel for etchant, an etchant trap, a pump connected to the vessel for etchant, a vacuum pump connected to the etchant trap, an etchant pen having a diagonally ended etching tip, having a valve controlling flow through the etching tip and having a vacuum tip adjoining the etching tip, diagonally ended oppositely from the etching tip, and extending forward beyond the etching tip, a connection from the bottom of the vessel for etchant to the etching tip through the valve and a connection from the etchant trap to the vacuum tip.

WILLIAM GUENST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 814,820 Wood Mar. 13, 1906 911,646 C'ook Feb. 9, 1909 1,188,870 Williamson June 27, 1916 FOREIGN PATENTS Number Country Date 388,411 France May 30, 1908 

